1. Field of the Invention
The invention relates to papermaking machine clothing and more particularly relates to an improved wet press felt for use on papermaking machines.
2. Brief Description of the Prior Art
The prior art is replete with descriptions of wet press felts; see for example the descriptions given in U.S. Pat. Nos. 3,097,413; 3,365,766; 3,401,467; 3,613,258; 4,107,367; 4,162,190; and 4,187,618. However, the prior art wet press felts have not been completely satisfactory in all respects. For example, a popular wet press felt is the so-called "batt-on-mesh" construction. In this particular wet press felt construction, a base on an open mesh screen type of fabric, in almost any weave pattern, is made up of multifilament and sometimes monofilament yarns. To this base fabric there is needled in 100 percent synthetic, textile staple fibers. The needling is accomplished in consecutive steps, as a plurality of webs or batts of the non-woven fibers are individually laid down on the base and needled in. Any desired thickness, weight and water permeability is achieved by the density of the webs or batts needled in. Although this type of wet press felt in widely employed and used, over a period of time it's usefulness deteriorates as compaction of the felt will occur, i.e.; a reduction in thickness and water permeability due to the repeated passage of the felt through the nip of the wet press rollers. The degree to which the felt will resist compaction during its use diminishes with time and use. As compaction of the felt occurs, the life of the felt shortens until the felt resists drainage of water through the felt. This, of course, reduces the efficiency of the papermaking machine and necessitates replacement of the felt with a new, uncompacted felt.
The wet press felt of the present invention resists compacting longer than the prior art wet press felts described above and therefore has a longer life in comparison to such prior art felts.